Brains scans are used to view the brain without actually having cranial surgery. They combine camera images with a computer to view what is going on inside someone's or something's head. Some scans are used to delineate the structure of particular diseases, other scans are used to find brain injuries or tumors, and still, others are used to study how the brain works. There are seven main scans that are used for testing today. These include Electroencephalography (EEG), Positron Emission Tomography (PET), Computerized Tomography (CT), Magnetic Resonance Imaging (MRI), Functional Magnetic Resonance Imaging (fMRI), Magneto Encephalography (MEG), and Near-Infrared Spectroscopy (NIRS).
             An electroencephalograph is attained by attaching electrodes to the skull, which measure electric brain waves in certain areas of the brain. These waves are then printed out so they can be read and studied. This technique is often used when people are sleeping, and also for testing people's reactions to certain things. Recently the EEG has been used to distinguish reaction times between people who have never been addicted to drugs or alcohol and people who have been addicted at some point. Scientists play a loud and abrasive noise, along with normal sounds repeated to test the difference in reaction times. The EEG then reports when their reaction is and how long it took. Studies by Henri Begleiter, professor of psychiatry and neuroscience at the State University of New York in Brooklyn, show that a normal person has a reaction time to a normal and predictable sound between 300 to 500 milliseconds. A person who is an alcoholic, even someone who has been abstinent for many years, has a reaction time that is much lower. This shows that they can not distinguish between new sounds and sounds that are predictable. This condition is called hyperexcitability, Begleiter suggests that people at risk for alcoholism inherit a general state of hyperexcitability and th...